This invention relates to a pitch measuring device which may be used to indicate, with precision, the amount of deviation of a first line or plane from a second or reference line in terms of a linear measure of rise or pitch per given unit of length. This is achieved through the combination of a frame with an assembled pitch vial wherein the inner diameter of a liquid and bubble containing vial cavity is larger at a first end than the second and, at a selected point on the vial axis gradually decreases radially as the distance from the first end increases.
Heretofor conventional level devices have been generally provided with one or more level and plumb indicating vials to indicate simply whether or not a given surface was horizontal or plumb without indicating the measured amount of deviation of the measured line from the horizontal or vertical reference line. Utilization of conventional level instruments by skilled artisans is fully satisfactory for level and plumb measurements but is unsatisfactory for applications calling for pitch calculation.
In an effort to improve the shortcomings of conventional prior art level instruments, various designs evolved which utilized spirit vials mounted on the level instruments as an element of a movable protractor type assembly. The vial and protractor assembly could be adjusted until the bubble in the vial indicated a given or selected level condition. The vial of such assemblies was typically provided with an indicator which was alignable with indicia on the protractor to indicate angular relationships of the measured surface after adjustment of the vial and protractor assembly. Devices of the type just described are more fully described in specification of the Wright, U.S. Pat. No. 4,073,062. While these patented devices were a needed step forward in the art, the need for careful adjustment made them slower than desirable in use, their complexity inhibited widespread use, and the relatively high manufacturing cost of such devices and consequent increased purchase price thereof reduced the size of their market.